Snap-fit or quick connectors have been found to be useful in a wide range of applications. In particular, they are frequently employed for joining fluid carrying conduit in automotive and industrial applications. Such connectors have found general acceptance in as they are typically capable of being closed in a single uniaxial movement which facilitates automated assembly, and entail simple designs which are relatively inexpensive to produce.
A further advantage of quick connect fittings is that they provide an effective seal for handling volatile or hazardous fluids such as gasoline while permitting ease of disassembly and reassembly during repair of a host system. Although tools are often required to effect release of quick connect fittings, designs such as those described in U.S. Pat. Nos. 3,990,727 and 4,844,512 provide for manual release of the fitting without the necessity of separate tools. Although representing an advancement in the art, such "squeeze-to-release" designs often have certain shortcomings.
In applications where hazardous material is to flow through a fitting, prevention of inadvertent release is of primary concern. Accordingly, relatively high axial pull-apart strength specifications are mandated. In order comply with such specifications, manufactures of prior art designs typically employed material with a relatively high characteristic flex modulus (such as glass filled Nylon 12) to prevent warping or deformation of abutting locking surfaces within the connector under axial loading conditions. Unfortunately, materials with increased flex modulus are inherently stiffer and can require substantially higher release forces. A related problem is found in that the stiffer material tolerates only relatively short radial displacement of the female connector abutment surface to effect release. This provides relatively little "purchase" (or degree of radial overlap) of the mating abutment surfaces in the engaged condition, thereby exacerbating potential pull apart problems.
Lastly, known prior art designs were prone to fatigue leading to failure after a relatively small number of engagement-disengagement cycles.